Silver halide emulsion containing a phosphoric acid amide

ABSTRACT

The light-sensitivity of a photographic material comprising at least one supported silver salt emulsion layer is improved by the addition of a water-soluble phosphoric acid amide as definded below.

United States Patent [1 1 Saleck et al.

[4 1 Oct. 28, 1975 1 SILVER I'IALIDE EMULSION CONTAINING A PHOSPI-IORICACID AMIDE [75] Inventors: Wilhelm Saleck, Schildgen;

Wolfgang Himmelmann, Opladen; Karl-Erwin Schnalke; Gerhard Balle, bothof Cologne, all of Germany [73] Assignee: Agfa-GevaertAktiengesellschaft,

Leverkusen, Germany [22] Filed: May 7, 1974 [2]] Appl. No.: 467,819

Related US. Application Data [63] Continuation of Ser. No. 309,279, Nov.24, 1972,

abandoned.

[30] Foreign Application Priority Data Nov. 30, 1971 Germany 2159379Primary ExaminerWon I-l. Louie, Jr. Attorney, Agent, or Firm-Connollyand Hutz [5 7] ABSTRACT The light-sensitivity of a photographic materialcomprising at least one supported silver salt emulsion layer is improvedby the addition of a water-soluble phosphoric acid amide as defindedbelow.

2 Claims, No Drawings SILVER HALIDE EMULSION CONTAINING A PHOSPHORICACID AMIDE This application is a continuation of the copending, U.S.Application Serial No. 309,279, filed November 24, 1972, entitledPhotographic Silver Salt Emulsion With Increased Sensitivity.

This invention relates to a photographic silver salt emulsion withincreased sensitivity which is achieved by the addition of phosphoricacid amides.

The sensitivity to light of a photographic silver salt emulsion can beinfluenced in two ways. Firstly, it can be increased by suitable choiceof the precipitation conditions and of the so-called physical ripening.In practice, the possibility of increasing the sensitivity in this wayis limited by the fact that the increase in sensitivity is accompaniedby an increase of the grain size, which deleteriously effect the qualityof the final image. It is therefore desired to obtain silver saltemulsions with a very high light-sensitivity but-fine grain.

Secondly, the sensitivity of photographic emulsions can be increased bychemical methods by adding compounds which are generally known aschemical sensitizers. In principle, these compounds could be added atany stage of the preparation of the emulsion, e.g. as ripening additivesbefore chemical ripening or to the finished casting solution afterchemical ripening. Ripening agents are e.g. noble metal salts,particularly gold salts, and sulfur compoundssuch as thiosulfates ororganic and particularly heterocylic sulfur compounds. A disadvantage ofthe chemical sensitization method is that the increase in sensitivity isaccompanied by an increased tendency of the emulsion to form an uniformfog which is capable of being developed. For this reason, very activechemical sensitizers such as compounds with an onium structure, e.g.quaternary ammonium or phosphonium salts or ternary sulfonium salts orpolyalkylene oxides and polyalkylene oxide derivatives can only be addedto the finished casting solution after chemical ripening. If suchsubstances were added before chemical ripening, the photographic silversalt emulsions would be so heavily fogged that they would be practicallyuseless.

None of the known chemical sensitizers adequately satisfies practicalrequirements, either because the increase in sensitivity achieved isinsufficient or because concomitant fogging prevents application of thesensitizer.

It is among the objects of the present invention to provide new chemicalsensitizers which do not have the above disadvantages and which increasethe lightsensitivity of photographic silver salt emulsions, inparticularly of photographic silver halide emulsions, without unwantedfogging.

We now have found a photographic material containing at least one silversalt emulsion layer which contains, as chemical sensitizer, awater-soluble phosphoric acid amide of the following formula:

wherein:

R is l) a hydrogen atom, (2) a saturated or olefinically unsaturatedaliphatic group, preferably an alkyl group and particularly an alkylgroup containing 1-3 carbon atoms, (3) an aryl group, in particular aphenyl group, which may be substituted, e.g. with an alkyl or alkoxygroup, both of which preferably contain up to 3 carbon atoms, acarboxyl, sulfo, sulfonamido, alkyl sulfonyl group, a halogen atom suchas fluorine, chlorine or bromine or a nitrile group, (4) cycloalkyl suchas a cyclopentyl or cyclohexyl group or (5) an acyl group, in particularacyl groups which are derived from organic sulfonic acids, such as alkylsulfonyl with alkyl groups which preferably contain up to 5 carbon atomsor phenyl sulfonyl in which the phenyl ring may contain additionalsubstituents, e.g. saturated or olefinically unsaturated aliphaticgroups which preferably contain up to 3 carbon atoms and which maythemselves contain substituents such as halogen, e.g. chlorine orbromine, alkoxy, phenoicy, sulfo groups or carboxyl groups; othersuitable substituents on the phenyl ring in addition to those mentionedabove are e.g. amino groups, alkylamino groups, diester groups ofsulfonylimido phosphoric acid or acylated amino groups, in particularwith radicals of saturated or. unsaturated aliphatic carboxylic acidswhich preferably contain up to 5 carbon atoms, v

R is (l) a hydrogen atom, (2) a saturated or olefinically unsaturatedaliphatic group, preferably an alkyl group and in particular an alkylgroup with 1-3 carbon atoms, (3) aryl, in particular a phenyl group,which may be substituted, e.g. with alkyl or alkoxy groups whichpreferably contain up to 3 carbon atoms, carboxyl, sulfo, sulfonamido oralkyl sulfonyl groupsor halogen such as fluorine, chlorine or bromine ornitrile, or (4) a cycloalkyl group, such as a cyclopentyl or cyclohexylgroup;

R is (l) a saturated or olefinically unsaturated aliphatic grouppreferably containing up to .5 carbon atoms, in particular an alkylgroup, (2) an aryl group, in particular a phenyl group, which may besubstituted as indicated for R, or (3) cycloalkyl, in particular acyclohexyl or cyclopentyl group.

In particular preferred are compounds of the following formula: 5

wherein:

R is (l) saturated or olefinically unsaturated alkyl having preferablyup to 3 carbon atoms which may be substituted with halogen such aschlorine or bromine, alkoxy having preferably up to 3 carbon atoms,phenoxy, sulfo or carboxyl, (2) amino, (3) alkylamino, (4) acylatedamino groups wherein the acyl radical is preferably derived from asaturated or olefinically unsaturated aliphatic carboxylic acids havingpreferably up to 5 carbon atoms, the acyl group may be derived from apolymeric aliphatic acid such as polyacrylic acid or polymethacrylicacid or copolymers of acrylic or methacrylic acid preferably withderivatives of these acids such as esters in particular with loweraliphatic alcohols having up to 5 carbon atoms, nitrils or amideswherein the amid groups may be substituted e.g. with ll \SOZNHHOR),groups or sulfo or sulfonamido wherein the amido group may besubstituted, for example, with The following are examples of suitablecompounds:

O OCH;

Copolymer of 50 Butylacrylate It is evident from the above table thatthe phosphoric acid amides used according to the invention may be eithermonomeric compounds or polymers. In the case of polymeric compounds, itis advantageous if the polymer contains at least 20 mol-% of activephosphoric acid amide units.

The molecular weight of the polymeric compound is in itself not criticalprovided that the polymer remains sufficiently soluble in water. Thesame applies to comonomers. The chemical structure of the comonomers isnot critical provided only that the photographic properties of theemulsion are not deleteriously affected by the comonomers and that thepolymer remains sufficiently soluble in water. Suitable olefinicallyunsaturated comonomers are e.g. unsaturated monoand dicarboxylic acids,e.g. acrylic acid and methacrylic acid or derivatives thereof such asesters, amides and nitriles, as well as crotonic acid, maleic acid,fumaric acid, itaconic acid as well as derivatives of these acids, inparticular their semi-esters and semi-amides, as well as vinyl compoundssuch as vinyl ether, in particular those which contain aliphatic ethergroups with up to 5 carbon atoms, e.g. vinylethyl ether or vinylisobutyl ether; furthermore, vinyl esters, in particular vinyl esters ofaliphatic carboxylic acids with up to 3 carbon atoms, e.g. vinyl acetateor vinyl chloroacetate, and in addition vinyl ketones such as vinylethylketone. A small percentage of hydrophobic comonomers such as olefines,e.g. ethylene, propylene or butylene, may of course also be present solong as the copolymer remains sufficiently water-soluble.

The preparation of the compounds used according to the invention isalready known. Reference may be made to the following publications:

A. v. KIRSANOV and N. L. EGOROVA, z.ob.-

Chim. 25, 187 (1955) A. V. KIRSANOV and V. l. SHEVCHENKO,

Z.ob6.Chim. 24, 882 (1954) A. V. KIRSANOV and V. I. SHEVCHENKO,

Z.obsc.Chim. 24, 1980 (1954). Phosphoric acid diester(N-acrylsulfonylamides), for example, are prepared as follows:

1st stage Sulfonylimino-phosphoric acid trichloride 2nd stage Phosphoricacid (N-sulfonylamide) dichloride 0.01 mol of sulfonylimino-phosphoricacid trichloride are dissolved in benzene and mixed with 0.01 mol ofanhydrous formic acid. Carbon monoxide and hydrogen chloride start toevolve after some time. The reaction mixture is left to stand at roomtemperature for -12 hours and then suction filtered.

3rd stage Phosphoric acid diester 0.3 mol of pyridine or triethylamineis slowly added dropwise with cooling at 010C to a solution of 0.1 molof phosphoric acid (N-sulfonylamide) dichloride in an alcohol. Stirringis continued for half an hour at room temperature after all the pyridineor triethylamine has been added and the solution is then concentrated byevaporation. 100 ml of water are added and the reaction mixture isslowly acidified to pH 2-3 with hydrochloric acid whilst cooling. Thereaction product which crystallizes is washed with water.

The photographic silver salt emulsions which are chemically sensitizedin accordance with the invention are prepared by the usual methods.Preparation of these emulsions comprises the following steps:

1. Precipitation of the silver salts, in particular silver halides, inthe presence of a protective colloid and physical ripening;

2. coagulation or flocculation of the emulsion and washing to remove thewater-soluble salts formed on precipitation, and

3. redispersion of the washed emulsion and chemical ripening.

The chemical sensitizer according to the invention are added to thephotographic silver salt emulsion before chemical ripening, preferablyat the stage of precipitation. The quantity required to he added depends.on the effect desired and can be determined in the usual manner by afew simple tests. Quantities of 1-50 g, based on g of gelatin originallyused for the emulsion, are generally sufficient. Based on the amount ofsilver halide to be precipitated, the amount required is ISO mg to 8 g,preferably 300 mg to 4 g, per mol of silver salt.

The substances used according to the invention are preferably added inthe form of their aqueous solutions. The concentration of the substancesin this solution is not critical and may vary within wide limits. Thephosphoric acid amides must be water-soluble to such an extent that itis possible to prepare an aqueous solution containing a sufficientquantity of active substance. It is sufficient, for example, to use al5% solution. In the case of very soluble substances, of course, a moreconcentrated solution may be used. The solutions are generally dissolvedat a pH of about 7 but the pH of the solution may be kept slightly acid,e.g. at pH values of between 5 and 7, or in the case of so-calledammonia emulsions the pH of the solution may be between 5 and Thesubstances according to the invention may be used in any silver saltemulsions, preferably in silver halide emulsions. Suitable silverhalides are silver chloride, silver bromide or mixtures of silverchloride and silver bromide, optionally with a small silver iodidecontent of up to 10 mol-%. The silver halides may be dispersed in theusual hydrophilic binders, for example in carboxymethyl cellulose,polyvinyl alcohol, polyvinyl pyrrolidone, alginic acid and its salts,esters or amides or proteins, preferably gelatin.

The emulsions may also contain other chemical sensitizers, e.g.quaternary ammonium and phosphonium salts or ternary sulfonium salts orreducing agents such as tin-ll-salts, polyamines such as diethylenetriamine or sulfur compounds as described in US. Pat. Specifi cation No.1,574,944. In addition, the given emulsions may contain salts of noblemetals such as ruthenium, rhodium, palladium, iridium, platinum or goldfor chemical sensitization, as described in the article by R. KOSLOWSKY,Z.Wiss.Phot. 46, 65-72 (1951). The emulsions may also containpolyalkylene oxides or polyalkylene oxide derivatives as developmentaccelerators or chemical sensitizers. An additional increase insensitivity is thereby achieved.

The emulsions may also be optically sensitized, e.g. with the usualpolymethine dyes such as neutrocyanines, basic or acid carbocyanines,rhodacyanines, hemicyanines, styryl dyes, oxonoles and the like.Sensitizers of this kind have been described in the work by F. M. HAMERThe Cyanine Dyes and related Compounds, lnterscience Publishers, adivision of John Wiley and Sons, New York (1964).

The emulsions may contain the usual stabilizers, e.g. homopolar or salttype compounds of mercury which contain aromatic or heterocyclic rings(for example mercaptotriazoles), simple mercury salts, sulfonium mercurydouble salts and other mercury compounds. Other suitable stabilizers areazaindenes, especially tetraor pentaazaindenes and particularly thosewhich are substituted with hydroxyl or amino groups. Compounds of thiskind have been described in the article by BlRR, Z.Wiss.Phot. 47, 2-58(1952). Other suitable stabilizers are e.g. heterocyclic mercaptocompounds such as phenyl mercaptotetrazole, quaternary benzothiazolederivatives, benzotriazole and the like.

The emulsions may be hardened in the usual manner, for example withformaldehyde or halogenated aldehydes which contain a carboxyl group,such as mucobromic acid, diketones, methane sulfonic acid esters,dialdehydes and the like or polyfunctional triazine derivatives such astris-acryloyl-hexahydrotriazine or halogenated or alkoxysubstitutedhexahydrotriazine derivatives.

The substances according to the invention exert their advantageouseffect not only in black and white emulsions but also in the productionof color photographic images. They are readily compatible with the usualcolor couplers. The phosphoric acid amides may also be used in directpositive emulsions, e.g. those with a composite grain structureaccording to French Pat. Specification No. 1,585,791.

They are also suitable for emulsions used in the silver dye bleachingprocess or dye diffusion process.

The phosphoric acid amides are particularly effective in those silversalt emulsions which are precipitated in the presence of silica sols.The preparation of such emulsions has been described in U.S. Pat.Specification According to another preferred embodiment, the phosphoricacid amides are used in combination with polymers which containdisulfonimide groups. Compounds of this kind have been described inGerman Pat. Specification No. 1,089,548 and in U.S. Pat. SpecificationNo. 3,052,656. The polymeric disulfonimides are added before chemicalripening, preferably at the stage of precipitation or flocculation. Theconcentration of the disulfonimides may vary within wide limits.Quantities of 1 to 10%, based on the original amount of gelatin, havebeen found to be sufficient.

EXAMPLE 1 SAMPLE l:

A neutral silver iodobromide gelatin emulsion containing 6 mol-% ofsilver iodide (average particle size 0.9 u) is precipitated. 100 g ofgelatin are used for precipitating 1 kg of silver halide. Afterprecipitation and physical ripening of the silver halide, the emulsionis cooled to 35C. It is flocculated in the usual manner with polystyrenesulfonic acid and acidified to pH 3.0 with 25% sulfuric acid. Theflocculate is left to precipitate and the supernatant solution isremoved. The flocculate is then washed twice with 20 litres of water byagitating the flocculate for minutes. After the final removal of thesupernatant water, the flocculate is dissolved in a suitable quantity ofwater and gelatin at pH 7 and 40C and treated with gold-Ill chloride andsodium thiosulfate as ripening additives and then ripened at a ripeningtemperature of 40C after the pAg value has been adjusted to 8.9.

SAMPLE 2 The emulsion is prepared in the same manner but duringprecipitation, 50 ml of a 7% aqueous solution of compound I are added tothe given gelatin/alkali metal halide solution.

Samples 2-17 are prepared in a similar manner by the addition of thesame amount of compounds 1-16 at the precipitation stage. All thesamples are then cast on a cellulose acetate support after the additionof the following additives per kg of emulsion, viz.: ml of a 5% aqueoussolution of saponin as wetting agent, 10 ml of a 10% aqueous solution offormaldehyde as hardener and ml ofa 1% methanolic solution of4-hydroxy-6- methyl-l ,3,3a,7-tetraazaindene as stabilizer. Afterdevelopment in a conventional sensitometer behind a step wedge anddevelopment (7 and 16 minutes at 20C) in a developer of the followingcomposition:

Sodium sulfite anhydrous 70.0 g borax 7.0 g hydroquinone 3.5 gpMonomethylaminophenol sulfate 3.5 g sodium citrate 7.0 g potassiumbromide 0.4 g

made up to 1 litre with water the results are assessedsensitometrically. From the following table it will be seen thatemulsions 2-17 are more sensitive than the comparison emulsion l.

7 minutes development 16 minutes development Sample Sensi- F Fog Sensi-F Fog tivity tivity 1 Typ 0.60 0.16 Typ 0,90 0,21 2 2 0.60 0.12 1 0.950,25 3 1 0.60 0,14 1,5" 0,85 0.23 4 +1,5 0,70 0.18 1 0,85 0.19 5 2 0.700.10 1.5 0.90 0.22 6 2 0.70 0,19 1 0,90 0.25 7 2 0,70 0.13 1 0.90 0,22 815 0.65 0.18 1 0,80 0.28 9 2 0,70 0,10 1 0,95 0.22 10 1.5 0.75 0.12 10.90 0.20 11 1 0.80 0,16 15 0.90 0,24 12 +1,5 0.75 0.12 1" 0.90 0.20 131 0,80 0,16 15 0.90 0,24 14 1 0.65 0.10 1 0,75 0.19 15 +1,5 0,70 0.11 10,85 0.21 16 15 0,65 0.13 1.5 0,80 0.21 17 2 0.70 0.16 1.5" 0.90 0,24

3 l shutter stop EXAMPLE 2 Samples 1 and 11 of Example 1 are comparedwith emulsion 18 which was prepared in the same way as emulsion 11 butwith the addition of 20 ml of a 20% aqueous solution of apolydisulfonimide of the formula at the precipitation stage.

All three emulsions are then processed as described R R" in Example 1.Nfi

in which Sensi- R is (1) an alkyl group having up to 3 carbon atoms,Sample tivity I Fog Sensitivity l Fog (2) a phenyl group, (3) acycloalkyl or 4 a Stand phenylsulfonyl group;

1 dard 0.60 0.15 Standard 0.90 0.25 to R2 is a y g atom, an alkyl grouphaving 11 15 0.65 0.13 15 0. up to 3 carbon atoms, (3) a phenyl group or(4) cy- 18 2.s 0.65 0.13 2.5" 0.95 0.23

cloalkyl, 3 l shutter stop R3 is 'O'R4 or R4 EXAMPLE 3 R is l an alkylgroup having up to 5 carbon atoms, SAM 1 20 (2) phenyl or (3)cycloalkyl; E l i 1 of E l 1 i d f comparison said amide being in aquantity sufficient to sensitize the material.

2. A process for the preparation of photographic sil- SAMPLE 2 verhalide emulsions by precipitation of the silver halide, physicalripening, flocculation or solidification and chemical ripening, whereinthe improvement comprises adding to the emulsion during precipitation aphosphoric acid amide of the following formula:

The emulsion of sample 11 of Example 1 is used.

SAMPLE 3 The emulsion of sample 11 of Example 1 is used but at theprecipitation stage of the alkali metal halide solution, 200 ml of a 30%silicic acid sol (pH 8.3, particle RI size about 14 nm, stabilized withNaOH) are added. N-P

The emulsion is then processed as described in Example l. The results ofthe sensitometric measurements are summarized in the table below.

1n wh1ch:

R is 1) an alkyl group having up to 3 carbon atoms,

(2) a phenyl group, (3) cycloalkyl or (4) a phenyl- 7 minutesdevelopment 16 minutes development time .1"... Sfllfonyl group, SampleSensi- I Fog S ensi- I Fog R 1s l) a hydrogen atom, (2) an alkyl grouphavlng up to 3 carbon atoms, (3) a phenyl group or (4) cy- 1 Standard0.60 0.16 Standard 0.90 0.21 cloalkyl; 2 2 0.70 0.10 +1" 0.95 0.22 a 4 33 0.70 0.12 1.s 1.00 0.22 R o R R2 3 l shutter stop 4 We claim: R

1. A photographic material comprising at least one R4 is an alkyl g phaving "P m 5 carbon atoms, supported silver halide emulsion layer whichcontains p y y y -a water-soluble phosphoric acid amide added duringsaid amide being in a quantity sufficient to sensitize the precipitationof the emulsion, said amide having the material. following formula:

1. A PHOTOGRAPHIC MATERIAL COMPRISING AT LEAST ONE SUPPORTED SILVERHALIDE EMULSION LAYER WHICH CONTANS A WATER-SOLUBLE PHOSPHORIC ACIDAMIDE ADDED DURING PRECIPITATION OF THE EMULSION, SAID AMIDE HAVING THEFOLLOWING FORMULA:
 2. A process for the preparation of photographicsilver halide emulsions by precipitation of the silver halide, physicalripening, flocculation or solidification and chemical ripening, whereinthe improvement comprises adding to the emulsion during precipitation aphosphoric acid amide of the following formula: